# Simple Harmonic Motion and hung spring

1. Jun 11, 2009

### grandprix

1. The problem statement, all variables and given/known data
A spring is hung from the ceiling. A 0.450-kg block is then attached to the free end of the spring. When released from rest, the block drops 0.150 m before momentarily coming to rest. (a) What is the spring constant of the spring? (b) Find the angular frequency of the block’s vibrations.

2. Relevant equations
Ei = Ef

$$\omega$$ = sqrt (k/m)

3. The attempt at a solution

I cant figure out how to find part A. I know that once I find that I take that value and plug it into equation 2 to solve for the angular frequency.

2. Jun 11, 2009

### Cyosis

During the entire motion of the spring two forces act on the block, which two forces?. During the instant the block is at rest how are these two forces related to each other?

3. Jun 11, 2009

### grandprix

gravity on the block and tension on the spring?

4. Jun 11, 2009

### Cyosis

Technically gravity and the restoring force of the spring. What about my second question?

5. Jun 11, 2009

### grandprix

sum of the forces = -kx

right?

6. Jun 11, 2009

### Cyosis

No, the sum of the forces=ma. During the instant the block is at rest, which force pulls harder, gravity or the restoring force?

7. Jun 11, 2009

### grandprix

gravity

8. Jun 11, 2009

### Cyosis

If gravity was pulling harder then why is the block at rest? If it was pulling harder it should be moving down. So same question again!

Last edited: Jun 11, 2009
9. Jun 21, 2009

### grandprix

Oh jeez i was making a careless mistake, I got the answer now!